In an attempt to clarify the situation, Gundogan posted a message on Facebook saying he will make his decision after Germany's European Championship qualifier against Gibraltar on Saturday 13 June.

"Normally I do not address media reports, especially not on Facebook. I want to this time to explain some things and give you a better insight," Gundogan wrote.

"Today I am in contract negotiations here, tomorrow I am having a medical check there. At first I could smile about it, but when there was talk of 'contract poker' and 'rip-off', that painted me in a bad light.

"Yesterday an ominous number [referring to reports of an exorbitant wage demand] appeared in the media and so I have decided to say something about it.

"The 2014-15 season ends on 30 June 2015. Although so far there have hardly been any transfers completed in Europe, rumour to rumour I was supposed to have demanded more and more, putting off making a final decision.

"Forgotten was this; I have one more year on my contract with Dortmund. What is important to me is that I am not gambling financially or using delaying tactics.

"What's next for me personally, I will reveal soon as possible. But only after the season and our important game for the European Championship qualifier with the national team will I decide."

Gundogan's comments suggest he could even decide to remain at Dortmund for the 2015-16 season and leave the club next summer on a free transfer.